A digital video recorder (DVR) system refers to a digital video storage device that stores a digital video signal in a large storage device such as a hard disk drive (HDD) and enables a user to play the digital video signal if necessary. Such the DVR system is also employed in a security system and compresses and processes video input from a plurality of security cameras and enables long-hour recording, a quick search, and a clear image playback. Also, the DVR system supports real-time video transmission and remote monitoring over the Internet by integrating a network function. Accordingly, the utility value of the DVR system is increasing.
An analog camera used for the DVR system may be classified based on image quality. For example, there are a low image quality camera having a video band of about 6 MHz and about 720 horizontal pixels (hereinafter, a video of such image quality is referred to as a “low image quality video”) and a recent high image quality camera having a video band of about 8 MHz and about 960 horizontal pixels (hereinafter, a video of such image quality is referred to as a “high image quality video”) to output a further vivid image. However, the DVR system requires image quality information of an input video to perform video processing such as video scaling, compressing, storing, or displaying. Only when a camera transmits video image quality information and the DVR system recognizes the video image quality information and is set in interaction with the video image quality information, the DVR system may be optimally utilized.
In general, a standard format of an analog video includes a national television system committee (NTSC) scheme in which a single frame includes 525 video lines and a phase alternation by line (PAL) scheme in which a single frame includes 625 video lines. While maintaining a standard format of an NTSC or PAL video signal without deformation or damage to video information, additional information such as a closed caption (CC) and a teletext may be transferred. In an analog video signal standard format, such additional information is included in a vertical blanking interval (VBI) and thereby transmitted using a characteristic that the additional information is not displayed on a screen in the VBI. Video image quality information between an analog camera and the DVR system may be transmitted using the VBI.
The resolution of a digital camera used for the DVR system may be classified into 720P, 1080I, and 1080P, and may be developed to be further diversified in the near future. Similar to the analog camera, even in the case of the digital camera, the DVR system requires image quality information of an input video to perform video processing such as video scaling, compressing, storing, or displaying. Only when a camera transmits video image quality information and the DVR system recognizes the video image quality information and is set in interaction with the video image quality information, the DVR system may be optimally utilized. However, when a video signal transmitted from the digital camera is transmitted using a serial digital interface (SDI), image quality information is included in digital information. Depending on cases, image quality information may be known by measuring the number of valid pixels included in video or measuring a clock frequency. For example, when the number of valid pixels is 720×1280 and a transmission clock is 74.25 MHz, the image quality may be determined as a 720P format.
The present invention has been made in an effort to outperform the aforementioned issues found in the related art and to provide a transmission scheme that may insert video image quality information and thereby transmit a video signal while maintaining a standard format of the video signal in an analog camera output, and enable a DVR system to determine a transmission scheme of the received video signal and video image quality of the received video signal and to differentiate video processing based on the determined video signal transmission scheme and video signal image quality, and to provide a video image quality adaptive DVR system. In detail, an analog camera inserts a signal (hereinafter, referred to as an “image quality determination signal”) having image quality information in a VBI of a video signal and thereby transmits the video signal to a DVR system. The DVR system determines whether the received video signal is an analog video signal or a digital video signal and converts the video signal to a component video signal and detects the image quality information using a video decoder when the received signal is the analog video signal, and converts the received video signal to a component video signal and detects the image quality information using a video receiver when the received video signal is the digital video signal, selects the component video signal and the video image quality information based on the determination of the video transmission scheme, and performs video processing, such as video scaling, compressing, storing, or displaying, on the selected component video based on the selected video image quality.